(function (win, lib) {
  let doc = win.document;
  let docEl = doc.documentElement;
  let metaEl = doc.querySelector('meta[name="viewport"]');
  let flexibleEl = doc.querySelector('meta[name="flexible"]');
  let dpr = 0;
  let scale = 0;
  let tid;
  let flexible = lib.flexible || (lib.flexible = {});

  if (metaEl) {
    console.warn("将根据已有的meta标签来设置缩放比例");
    let match = metaEl
      .getAttribute("content")
      .match(/initial\-scale=([\d\.]+)/);
    if (match) {
      scale = parseFloat(match[1]);
      dpr = parseInt(1 / scale);
    }
  } else if (flexibleEl) {
    let content = flexibleEl.getAttribute("content");
    if (content) {
      let initialDpr = content.match(/initial\-dpr=([\d\.]+)/);
      let maximumDpr = content.match(/maximum\-dpr=([\d\.]+)/);
      if (initialDpr) {
        dpr = parseFloat(initialDpr[1]);
        scale = parseFloat((1 / dpr).toFixed(2));
      }
      if (maximumDpr) {
        dpr = parseFloat(maximumDpr[1]);
        scale = parseFloat((1 / dpr).toFixed(2));
      }
    }
  }

  if (!dpr && !scale) {
    let isAndroid = win.navigator.appVersion.match(/android/gi);
    let isIPhone = win.navigator.appVersion.match(/iphone/gi);
    let devicePixelRatio = win.devicePixelRatio;
    if (isIPhone || isAndroid) {
      // iOS下，对于2和3的屏，用2倍的方案，其余的用1倍方案
      if (devicePixelRatio >= 3 && (!dpr || dpr >= 3)) {
        dpr = 3;
      } else if (devicePixelRatio >= 2 && (!dpr || dpr >= 2)) {
        dpr = 2;
      } else {
        dpr = 1;
      }
    } else {
      // 其他设备下，仍旧使用1倍的方案
      dpr = devicePixelRatio;
    }
    scale = 1 / dpr;
    // scale = 1 * dpr;
  }

  docEl.setAttribute("data-dpr", dpr);
  if (!metaEl) {
    metaEl = doc.createElement("meta");
    metaEl.setAttribute("name", "viewport");
    metaEl.setAttribute(
      "content",
      "initial-scale=" +
        scale +
        ", maximum-scale=" +
        scale +
        ", minimum-scale=" +
        scale +
        ", user-scalable=no"
    );
    if (docEl.firstElementChild) {
      docEl.firstElementChild.appendChild(metaEl);
    } else {
      let wrap = doc.createElement("div");
      wrap.appendChild(metaEl);
      doc.write(wrap.innerHTML);
    }
  }

  function refreshRem() {
    let width = docEl.getBoundingClientRect().width;
    let height = docEl.getBoundingClientRect().height;

    if (width / dpr < 1400) {
      width = 1920 * dpr;
    }
    let rem = (width * dpr) / 10;
    docEl.style.fontSize = rem + "px";
    flexible.rem = win.rem = rem;
    // if(width>3040&&width<3640){
    //   docEl.style.fontSize = 1 + "px";
    //   flexible.rem = 1 + "px";
    // }
  }
  win.addEventListener(
    "resize",
    function () {
      refreshRem();
    },
    false
  );
  win.addEventListener(
    "pageshow",
    function (e) {
      if (e.persisted) {
        refreshRem();
      }
    },
    false
  );

  if (doc.readyState === "complete") {
    doc.body.style.fontSize = 12 * dpr + "px";
  } else {
    doc.addEventListener(
      "DOMContentLoaded",
      function () {
        doc.body.style.fontSize = 12 * dpr + "px";
      },
      false
    );
  }

  refreshRem();

  flexible.dpr = win.dpr = dpr;
  flexible.refreshRem = refreshRem;
  flexible.rem2px = function (d) {
    let val = parseFloat(d) * this.rem;
    if (typeof d === "string" && d.match(/rem$/)) {
      val += "px";
    }
    return val;
  };
  flexible.px2rem = function (d) {
    let val = parseFloat(d) / this.rem;
    if (typeof d === "string" && d.match(/px$/)) {
      val += "rem";
    }
    return val;
  };
})(window, window["lib"] || (window["lib"] = {}));

